--- /dev/null
+/*
+ * Copyright 2023 The OpenSSL Project Authors. All Rights Reserved.
+ *
+ * Licensed under the Apache License 2.0 (the "License"). You may not use
+ * this file except in compliance with the License. You can obtain a copy
+ * in the file LICENSE in the source distribution or at
+ * https://www.openssl.org/source/license.html
+ */
+
+/*
+ * NB: Changes to this file should also be reflected in
+ * doc/man7/ossl-guide-tls-client-non-block.pod
+ */
+
+#include <string.h>
+
+/* Include the appropriate header file for SOCK_STREAM */
+#ifdef _WIN32 /* Windows */
+# include <winsock2.h>
+#else /* Linux/Unix */
+# include <sys/socket.h>
+# include <sys/select.h>
+#endif
+
+#include <openssl/bio.h>
+#include <openssl/ssl.h>
+#include <openssl/err.h>
+
+/* Helper function to create a BIO connected to the server */
+static BIO *create_socket_bio(const char *hostname, const char *port)
+{
+ int sock = -1;
+ BIO_ADDRINFO *res;
+ const BIO_ADDRINFO *ai = NULL;
+ BIO *bio;
+
+ /*
+ * Lookup IP address info for the server.
+ */
+ if (!BIO_lookup_ex(hostname, port, BIO_LOOKUP_CLIENT, 0, SOCK_STREAM, 0,
+ &res))
+ return NULL;
+
+ /*
+ * Loop through all the possible addresses for the server and find one
+ * we can connect to.
+ */
+ for (ai = res; ai != NULL; ai = BIO_ADDRINFO_next(ai)) {
+ /*
+ * Create a TCP socket. We could equally use non-OpenSSL calls such
+ * as "socket" here for this and the subsequent connect and close
+ * functions. But for portability reasons and also so that we get
+ * errors on the OpenSSL stack in the event of a failure we use
+ * OpenSSL's versions of these functions.
+ */
+ sock = BIO_socket(BIO_ADDRINFO_family(ai), SOCK_STREAM, 0, 0);
+ if (sock == -1)
+ continue;
+
+ /* Connect the socket to the server's address */
+ if (!BIO_connect(sock, BIO_ADDRINFO_address(ai), BIO_SOCK_NODELAY)) {
+ BIO_closesocket(sock);
+ sock = -1;
+ continue;
+ }
+
+ /* Set to nonblocking mode */
+ if (!BIO_socket_nbio(sock, 1)) {
+ sock = -1;
+ continue;
+ }
+
+ /* We have a connected socket so break out of the loop */
+ break;
+ }
+
+ /* Free the address information resources we allocated earlier */
+ BIO_ADDRINFO_free(res);
+
+ /* If sock is -1 then we've been unable to connect to the server */
+ if (sock == -1)
+ return NULL;
+
+ /* Create a BIO to wrap the socket*/
+ bio = BIO_new(BIO_s_socket());
+ if (bio == NULL)
+ BIO_closesocket(sock);
+
+ /*
+ * Associate the newly created BIO with the underlying socket. By
+ * passing BIO_CLOSE here the socket will be automatically closed when
+ * the BIO is freed. Alternatively you can use BIO_NOCLOSE, in which
+ * case you must close the socket explicitly when it is no longer
+ * needed.
+ */
+ BIO_set_fd(bio, sock, BIO_CLOSE);
+
+ return bio;
+}
+
+static void wait_for_activity(SSL *ssl, int write)
+{
+ fd_set fds;
+ int width, sock;
+
+ /* Get hold of the underlying file descriptor for the socket */
+ sock = SSL_get_fd(ssl);
+
+ FD_ZERO(&fds);
+ FD_SET(sock, &fds);
+ width = sock + 1;
+
+ /*
+ * Wait until the socket is writeable or readable. We use select here for
+ * the sake of simplicity and portability, but you could equally use
+ * poll/epoll or similar functions
+ */
+ if (write)
+ select(width, NULL, &fds, NULL, NULL);
+ else
+ select(width, &fds, NULL, NULL, NULL);
+}
+
+static int handle_io_failure(SSL *ssl, int res)
+{
+ switch (SSL_get_error(ssl, res)) {
+ case SSL_ERROR_WANT_READ:
+ /* Temporary failure. Wait until we can read and try again */
+ wait_for_activity(ssl, 0);
+ return 1;
+
+ case SSL_ERROR_WANT_WRITE:
+ /* Temporary failure. Wait until we can write and try again */
+ wait_for_activity(ssl, 1);
+ return 1;
+
+ case SSL_ERROR_ZERO_RETURN:
+ /* EOF */
+ return 0;
+
+ case SSL_ERROR_SYSCALL:
+ return -1;
+
+ case SSL_ERROR_SSL:
+ /*
+ * If the failure is due to a verification error we can get more
+ * information about it from SSL_get_verify_result().
+ */
+ if (SSL_get_verify_result(ssl) != X509_V_OK)
+ printf("Verify error: %s\n",
+ X509_verify_cert_error_string(SSL_get_verify_result(ssl)));
+ return -1;
+
+ default:
+ return -1;
+ }
+}
+
+/* Server hostname and port details. Must be in quotes */
+#ifndef HOSTNAME
+# define HOSTNAME "www.example.com"
+#endif
+#ifndef PORT
+# define PORT "443"
+#endif
+
+/*
+ * Simple application to send a basic HTTP/1.0 request to a server and
+ * print the response on the screen.
+ */
+int main(void)
+{
+ SSL_CTX *ctx = NULL;
+ SSL *ssl = NULL;
+ BIO *bio = NULL;
+ int res = EXIT_FAILURE;
+ int ret;
+ const char *request =
+ "GET / HTTP/1.0\r\nConnection: close\r\nHost: "HOSTNAME"\r\n\r\n";
+ size_t written, readbytes;
+ char buf[160];
+ int eof = 0;
+
+ /*
+ * Create an SSL_CTX which we can use to create SSL objects from. We
+ * want an SSL_CTX for creating clients so we use TLS_client_method()
+ * here.
+ */
+ ctx = SSL_CTX_new(TLS_client_method());
+ if (ctx == NULL) {
+ printf("Failed to create the SSL_CTX\n");
+ goto end;
+ }
+
+ /*
+ * Configure the client to abort the handshake if certificate
+ * verification fails. Virtually all clients should do this unless you
+ * really know what you are doing.
+ */
+ SSL_CTX_set_verify(ctx, SSL_VERIFY_PEER, NULL);
+
+ /* Use the default trusted certificate store */
+ if (!SSL_CTX_set_default_verify_paths(ctx)) {
+ printf("Failed to set the default trusted certificate store\n");
+ goto end;
+ }
+
+ /*
+ * TLSv1.1 or earlier are deprecated by IETF and are generally to be
+ * avoided if possible. We require a minimum TLS version of TLSv1.2.
+ */
+ if (!SSL_CTX_set_min_proto_version(ctx, TLS1_2_VERSION)) {
+ printf("Failed to set the minimum TLS protocol version\n");
+ goto end;
+ }
+
+ /* Create an SSL object to represent the TLS connection */
+ ssl = SSL_new(ctx);
+ if (ssl == NULL) {
+ printf("Failed to create the SSL object\n");
+ goto end;
+ }
+
+ /*
+ * Create the underlying transport socket/BIO and associate it with the
+ * connection.
+ */
+ bio = create_socket_bio(HOSTNAME, PORT);
+ if (bio == NULL) {
+ printf("Failed to crete the BIO\n");
+ goto end;
+ }
+ SSL_set_bio(ssl, bio, bio);
+
+ /*
+ * Tell the server during the handshake which hostname we are attempting
+ * to connect to in case the server supports multiple hosts.
+ */
+ if (!SSL_set_tlsext_host_name(ssl, HOSTNAME)) {
+ printf("Failed to set the SNI hostname\n");
+ goto end;
+ }
+
+ /*
+ * Ensure we check during certificate verification that the server has
+ * supplied a certificate for the hostname that we were expecting.
+ * Virtually all clients should do this unless you really know what you
+ * are doing.
+ */
+ if (!SSL_set1_host(ssl, HOSTNAME)) {
+ printf("Failed to set the certificate verification hostname");
+ goto end;
+ }
+
+ /* Do the handshake with the server */
+ while ((ret = SSL_connect(ssl)) != 1) {
+ if (handle_io_failure(ssl, ret) == 1)
+ continue; /* Retry */
+ printf("Failed to connect to server\n");
+ goto end; /* Cannot retry: error */
+ }
+
+ /* Write an HTTP GET request to the peer */
+ while (!SSL_write_ex(ssl, request, strlen(request), &written)) {
+ if (handle_io_failure(ssl, 0) == 1)
+ continue; /* Retry */
+ printf("Failed to write HTTP request\n");
+ goto end; /* Cannot retry: error */
+ }
+
+ do {
+ /*
+ * Get up to sizeof(buf) bytes of the response. We keep reading until
+ * the server closes the connection.
+ */
+ while (!eof && !SSL_read_ex(ssl, buf, sizeof(buf), &readbytes)) {
+ switch (handle_io_failure(ssl, 0)) {
+ case 1:
+ continue; /* Retry */
+ case 0:
+ eof = 1;
+ continue;
+ case -1:
+ default:
+ printf("Failed reading remaining data\n");
+ goto end; /* Cannot retry: error */
+ }
+ }
+ /*
+ * OpenSSL does not guarantee that the returned data is a string or
+ * that it is NUL terminated so we use fwrite() to write the exact
+ * number of bytes that we read. The data could be non-printable or
+ * have NUL characters in the middle of it. For this simple example
+ * we're going to print it to stdout anyway.
+ */
+ if (!eof)
+ fwrite(buf, 1, readbytes, stdout);
+ } while (!eof);
+ /* In case the response didn't finish with a newline we add one now */
+ printf("\n");
+
+ /*
+ * The peer already shutdown gracefully (we know this because of the
+ * SSL_ERROR_ZERO_RETURN (i.e. EOF) above). We should do the same back.
+ */
+ while ((ret = SSL_shutdown(ssl)) != 1) {
+ if (ret < 0 && handle_io_failure(ssl, ret) == 1)
+ continue; /* Retry */
+ /*
+ * ret == 0 is unexpected here because that means "we've sent a
+ * close_notify and we're waiting for one back". But we already know
+ * we got one from the peer because of the SSL_ERROR_ZERO_RETURN
+ * (i.e. EOF) above.
+ */
+ printf("Error shutting down\n");
+ goto end; /* Cannot retry: error */
+ }
+
+ /* Success! */
+ res = EXIT_SUCCESS;
+ end:
+ /*
+ * If something bad happened then we will dump the contents of the
+ * OpenSSL error stack to stderr. There might be some useful diagnostic
+ * information there.
+ */
+ if (res == EXIT_FAILURE)
+ ERR_print_errors_fp(stderr);
+
+ /*
+ * Free the resources we allocated. We do not free the BIO object here
+ * because ownership of it was immediately transferred to the SSL object
+ * via SSL_set_bio(). The BIO will be freed when we free the SSL object.
+ */
+ SSL_free(ssl);
+ SSL_CTX_free(ctx);
+ return res;
+}
projects / thirdparty / openssl.git / commitdiff
